Devices for imparting rotation to a boom are well known in the art. One such device is described in U.S. Pat. No. 3,964,512 which discloses a pipe boom used in conjunction with a slurry pump for delivering and placing concrete. The boom is rotated by an externally mounted drive sprocket secured to the boom shaft and rotated by a chain which extends around the drive sprocket and the gear of a motor. In such chain driven devices, the chain tends to expand and wear after extended use and fit sloppily around the sprocket. Also, such structures are inherently dangerous inasmuch as an individual may be injured by placing his fingers too close to the externally mounted drive assembly and accidentally getting his fingers caught between the sprocket and chain.
It is, therefore, an object of the present invention to provide a linear movable apparatus for imparting rotational movement to an object.
It is a further object of the present invention to provide the apparatus with a rack and pinion type drive mechanism having means for retaining the gears of the rack and pinion drive in snug fitting engagement.
It is yet a further object of the present invention to provide such a drive mechanism with means for enclosing the rack and pinion drive mechanism to protect the drive mechanism and to also serve to protect an individual from injury by the drive mechanism.